Final answer:
The energy level for an electron with the quantum numbers (3, 2, -1, -1/2) is the third energy level, as indicated by the principal quantum number 3.
Step-by-step explanation:
The energy level for an electron is determined by the first of the four quantum numbers, which is known as the principal quantum number (n). In the given set of quantum numbers (3, 2, -1, -½), the first number, 3, represents the principal quantum number, which indicates that the electron is in the third energy level or shell. According to Bohr's model of the atom and quantum theory, the higher the principal quantum number, the higher the energy level of the electron in the atom.